Scenario-based flood adaption of a fast-developing delta city: Modeling the extreme compound flood adaptations for Shanghai

Hangxing Wu (Lead Author), Min Zhang, Yi He, Peiyan Chen, Ulysse Pasquier, Hengzhi Hu, Jiahong Wen

Research output: Contribution to journalArticlepeer-review

Abstract

The heavy Zhengzhou "7·20" rainstorm, partially caused by Typhoon In-fa in 2021, poured an unprecedented rainfall of 201.9 mm/h, leading to severe flooding and damage. Although many studies in various Chinese cities have preliminarily assessed the potential flood losses under "7·20" rainstorm, much research has focused on the contribution of climate change, limited attention has been paid to the potential impacts of urbanization development, which is crucial for designing flood adaptation strategies. Using high-resolution ocean-land coupled numerical model, we focus on Shanghai, a fast-developing delta city, to evaluate the potential impact of "7·20" rainstorm associated with local coastal storm hazards for flood adaptation planning under future urbanization scenarios. Our findings reveal that rapid urbanization in Shanghai can significantly amplify flood risks caused by events equivalent to "7·20" rainstorm. By 2050, the projected increases in exposed assets and losses can be up to 8 and 5 times, respectively, if such events occur. The adaptation measure of heightening seawalls and dikes provides robust protection against compound fluvial-coastal flooding events, but is costly and less effective against pluvial flooding. In contrast, low-impact development measures of increasing green area may not offer the highest asset exposure reduction but have low initial costs and provide significant ecological benefits. Lowering green space offers the greatest reduction in exposed assets and losses from pluvial flooding, but it’s also costly and may alter the urban landscape. A combination of these measures, where applicable, is recommended to optimize flood resilience and promote sustainable development in rapidly urbanizing delta cities.
Original languageEnglish
Article number105207
JournalInternational Journal of Disaster Risk Reduction
Volume117
Early online date13 Jan 2025
DOIs
Publication statusPublished - 1 Feb 2025

Keywords

  • 20″ rainstorm
  • Coastal adaptation
  • Delta city
  • Numerical modeling
  • Rapidly urbanization
  • Zhengzhou "7

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